Altitude control for airplane engine throttler



Jul A12 1927.

y F. c. MocK ET Al.

ALTITUDE CONTROL FOR AIRPLANE ENGINE THnoTTLEs Filed June 12. 1920 3 Sheets-Sheet I By ma;

@Qi/S.

192 July lz 7 F. c. MocK ET AL 'ALTITUDE CONTROL FOR AIRPLANE ENGINE THROTTLES Filed June 12, 1920 s sheets-sheet z Ilfllmmw F. C. MOCK ET AL ALTITUDE CONTROL Fon AIRPLANE ENGINE THROTTLES Filed June 12. 1920v s sheets-sheet 3 Patented July 12, 1927.

UNITED STATES y 1,635,492 PATENT oFFlcE. 1

' FRANK C. MOCK, CHARLES Il'.- GUSTAFSON, AND MILTON E.v CHANDLER, OF CHICAGO,

l ILLINOIS, ASSIGNORS TO STROMBERG MOTOR DEVICES COMPANY, OF CHICAGO,

ILLINOIS, A CORPORATION OF ILLINOIS.

ALTITUDE CONTROL Eon AIEPLANE ENGINE THEOTTLES.'

Application led June 12, 41920. Serial No. 388,478.

A This invent-ion relates broadly to means for controlling the speed of an internal combustion engine in accordance with changes in barometric conditions of the at- 5 lnosphere at different altitudes.

In the present development of the internal combustion engine for aviation duty the engine is designed to-operate for the most part at relatively high altitudes, and this means l that maximum power and efficiency will be obtained only by establishment of a relatively high compression ratio in the engine, in view of the rarelied condition of air at high altitudes. This results in pre-ignition, loss of l power, undue wearnon the engine, and pos,-

sible fracture of the parts if the engine is. operated with a full charge explosive mixture on the ground. It` has been generally regarded as impracti'cable to depend upon 20 the pilots of the planes to properly regulate the throttle position when on the ground; one well known attempt being that of constructing the carburetor whereb a full opening of the throttle at low altitude will obtain 5 avery lean mixture. This has the eliect that in combat, if after making a so-called dive the pilot should attempt to come out of. it by i"suddenly opening the throttle, the engine would not fire, thus placing the pilot in great danger.

We have devised 'several ways of overcoming the faults of and objection to the present practice as outlined above, which we will describe in detail later; but, broadly speaking, we place the manually operated throttle of the engine, which is usually at the carburetor, subject to means sensitive to changes in barometric conditions of the atmosphere. In other words, full open throttle cannot be had when on the ground, butl at a reasonablealtitude, or upon a .change in atmospheric conditions, such as are encountered at the altitudes in which an airplane usually operates, the manual control of the throttle is unrestricted, giving thepilot full control of his machine.

4One of the methods of control which we employ consists in limiting the movement of' the throttle beyond a certain predetermined point when in sea level pressures. Another method controls the manual manipulation of the throttle throughout its entire range of movement, and a further method, which is perhaps the most desirable of the -threegcontrols the position ot' the throttle principle being mechanically different.

We shall describe inl detail 'the preferred structures which we employ, but do not desire it understood that we limit ourselves to the means employed to reach the end in view.

A more concrete understandingof our invention may be obtained from the following detall description and the appended claims, taken 1n connection with the accompanying drawings, in which:

Figure 1 is a' fragmentary view of one form of our invention;

Flgure 2 is a similar View, partly in section, of a modifled form of our invention, shown in side elevation; A

Figure 3 is a similar view in end elevation; and

Figure 4 is a top plan of the same;

Figure 5 is a furtherl modified form of the invention, shown in'section and in fragmentary assembly; and c i Figure 6v is a sectional view taken .on the line 6-6 of Figure 5.

Referring in detail to the irst form of our lnvention, namely that illustrated in Figure 1, yl() designates the mixing chamber of a conventional form of carburetor, and 11 designates the float chamber thereof.

A throttle 12 ofthe butterfly type is shown in dotted lines, and is carried by a shaft l13 in the usual manner, one end of the shaft projecting beyond the mixing chamber to receive a lever 14 adapted to move with said shaft. The lever 14 has a long arm 15 and a short arm 16, the arm l5 having connection at its free end, by a universal joint 17, with the rod 18 which is operated from the cock-pit of the plane or from any other convenient point.

The operators or pilots lever 19 isl pivoted at 20 for movement over a segment-al rack 21 'of the usual construction, the lever 19 having a. short arm 22 provided with an opening 23 through which the rod 18 extends, the opening 23 being countersunk to accommodate the rod at dilerent angles. Movement of the rod 18 to close the throttle is accomplished through a collar 24 fixed on said rod against which the arm` 22 of the lever 19 abuts, and movement of said rod 18 in the vopposite direction for openingr the throttle is obt-ained by a collar 25 slidable on said rod and having a coiled spring 26 behind it, which abuts a third collar 27 anchored to the free end of the rod. The

pur be ascribed presently. The short arm 16 of the lever 14 is provided with a laterally extending pin 16' for a purpose which will hereinafter appear.

The foregoing describes a particular form of manual control means for setting the throttle in accord-ance with the desires of the operator modified so as to facilitate its association with the barometric control, which we will now proceed to describe.

lVe provide an expansible bellows 28 mounted Within a pro-tective casing` 29 on the extension 30 of the mixing chamber 10. The expansible bellows conta-ius dry air or gas at Sea level temperature and -pressure or any other substantially fixed pressure 'of greater or less degree. cylinder 31 is concentrically arranged in the bellows and serves to guide a plunger 32 carried by and movable with said, bellows. A plunger rod 33 seats within the plunger on the lower end thereof and a properly calibrated coiled spring 34 surrounds the rod 33 and is interposed between the head 35 of said rod and the top of the casing 29. The rod extends without y the casing through an opening 36 which is sufficiently large to allow for lateral displacement of the rod in use. Said rod is pivotally con nected to a control lever 37 in turn pivoted at 38 on the standard 39. The free end of the lever 37 is disposed adjacent toand is adapted to oscillate vertically past the shaft 13, the lever 37 being formed with a shoe on its free end which is, at atmospheric temperature and pressure, disposed in the path of movement of the pin 16', thereby limiting effectively the degree to which the throttle may be opened..y

In the operation of this form of our invention the spring 33 and bellows are so calibrated that at normal 'atmospheric temperature and preure the lever 37 will be maintained in the position shown in Figure 1, thereby limiting the degree to which the throttle may be opened to about one-half or five-eighths. When the plane on which the carburetor is installed starts to ascend and reaches a height between 2,500 and 3,000 feet or more, the atmosphere at such an altitude becomes rarefied and, thel pressure consequently drops permittingthe bellows to expand against the tension of the spring 34 to raise the lever 37. It will be noted that the curvature of the shoe 40 is eccentric of the spring and its function will usamos to the pivot 38 of the lever 37, this curvature being determined -by experiment and the lever 37 will-bey in the dotted line position shown in Figure l, permitting full opening of the throttle. Should the pilot attempt to open the throttle to the full position when on the ground the pin 16 will engage the shoe 40 and thus limit thc movement of the throttle. I 19 is permitted to move 4through the entire arc of the segment 21, the collar 25 moving along the rod 18 and compressing the spring 26 for this purpose.

In the form of the invention just described, free opening and closing of the throttle between the limits set by the barometric unit is permitted. In the form of the invention illustrated in Figures 2 to 4 However, the lever inclusive, is disclosed a modification wherein uniform action of the throttle in response to the manual control is had from closed to the limiting opening position, the full travel of the pilot lever being effective at all times, the effectiveness only of this travel being controlled. In other words, the manually operated lever has the same percentage of throttle at all times,the tot-al travel of the throttle being vvaried by altering the re. lations of the Various links between the throttle and the manual control lever to obtain the desired result.

Now referring to Figures 2 to 4 inclusive, the mixing chamber 42 of a conventional form of carburetor is shown, the mixing chamber having the usual outlet 43 to the intake-manifold 42 of an internal combustion engine and a butterfiy throttle valve 44 located in said outlet. The butterfiy valve 44 is carried by a shaft 45 which projects through a suitable bearing 46 to the exterior of the mixing chamber 42 and carries a crank 47 thereon, said crank being offset at 48 and carrying a stub-shaft 49 on which is mounted a roller 50.

The control mechanism for the throttle valve is mounted on a frame 51, this frame having a head portion 52 which is 'adapted to partly encircle the mixing chamber and engage beneath 4the flange 53 formed on'the,

upper end thereof, the bolts 54 serving to securely support said frame 51 on thencarburetor` as well as connect thc carburetor to the intake manifold.

The frame 51 is provided with a foot por- In order to insure rigidity-of the Lesa-:oa

piece 5, said extension 59 having a bolt 60 passing therethrough and engaging 1n the an' intake of the carburetor. 0f course, we

do not limit ourselves to the mounting of'thc threaded at 64 and receives a. nut 65 theref on.

An interiorly threaded sleeve 66 is engaged in the threaded portion 64 of the rod 6l and is provided with an enlarged flange portion 67 which facilitates rotation of the sleeve. The sleeve is provided with a similar flange .68 on the opposite end` said flanges performing additional functions to be set forth later. A cap nut 69 is threaded at 70 into an arm 71 cast integrally with the frame or bracket 51, said cap nut having a hollow chamber 72 and an opening 73 at the tcp thereof through which the upper free end of the rod -61 is adapted to pass. A coiled spring 74 is interposed between the top lof the nut 69 and the upper flange of the collar 66.

As pointed out hereinbefore, this form of the invention is such that the manual control lever is effective throughout its 'entire range of travel, but owing toa regulation of the effectiveness of that travel, the degree to which the throttle is opened, is determined. The means by which this is accomplished consists, in combination with the bellows described hereinbeforc, of an arm 75 pivoted at 76 on an extension 77 integrally formed on the bracket 51, said arm 75 having a forked extension 78, the arms of which are disposed between the flanges 67 and 68 of the sleeve 66 and adapted to embrace thel central portion of said sleeve. The arm 75 extends to a point adjacent to the crank 47 described hereinbefore and serves as an adjustable fulcrum for the manually controlled lever 7,9, said lever being pivoted at 80 on the free end of said arm 75. The pivot points of said arm 7 5 and said arm 79 are. in the form of machine screws or bolts, but of course it will be understood that variations may be had in this structure such as do not materially depart from the spirit of the invention. The arm 79 is normally disposed downwardly approximately at the angle shown and is provided with an aperture 81 in its lower end toI which is connected the manually operated throttle lever which is located in the cock-pit of the plane or at any other convenient point. The other end of the lever 79 extends upwardly in relatively slight angular relation to the main portion of the arm 75 and is provided with a forked portion 82 whichis adapted to receive and vembrace the i'oller 50 mounted on the pin 49 carried by the crank 47.

In order to limit the moyement of the arm 75 upwardly a lug 83 is formed on the inner side thereof and carries' a stop screw 84 which is adapted to engage the surface of the stop 85 formed integrally with the bracket 51. 4Movement of the crank 47 is similarly limited, a lug 86 being formed thereon.

'lhe movement of the lever 79 is similarly limited, a lug 86 being formed thereon and carrying a stop screw 87 which is adapted to engage the upper inclined surface 8,8 of the sto 85. t y,

Int ie operation of this form of our in; vention the expansible bellows, being sealed and containing dry air or gas at sea level temperature and pressure, or any fixed pressure of greater or less degree will expand as the plane rises to greater altitudes or upon changes to atmospheres of less density than that found .at sea level temperature and pressure. The expanding of the bellows under these conditions will move the arm 75 downwardly, thus increasing the effective arc of travel of the fork 82 carried by the arm 79. Thus when on the ground, that being the condition which the parts have been shown in, movement of the lever 79 to the `left will impart a given movement, approximately one-half to five-eighths' of the travel of thethrottle. and this will be-increased proportionately as the plane ascends owing to the fact that the effective stroke of the forked member 82 is increased as the bellows expands. Thus it will be readily apparent that while the opera-tor can move the manual control through the entire range of movement, the effectiveness of this movement is limited by the position of the bellows in accordance with barometric conditions.

While the forms of our invention described hereinbefore contain advantageous features not found in .the prior art, they both possess the defect that they permit the same throttle opening for all speeds, that is, with the motor idling, on the ground the operator can open the throttle suddenly far enough to give the engine a full charge at this low speed, and thereby subject .it to harmful strains prior to picking up speed.

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In some respects the strain of pre-ignition at I which embodies a method of controlling the degree of throttle opening directly in proportion to the speed, or rather, in 'propormanifold.

In this form of the invention the carburetor 90 connected to manifold 91 and having the butterfly throttle valve 92, is con-V tion to the density of the charge in the intake communication with the-intake manifold on the engine side of the throttle through a conduit 98. i. The lcasing contains an expan-- sible bellows`99 `anchored at 1.00 to one end of said casing, the end wall 101 of said casing being concavo-convex so that said bellows may have a relatively large air content to prevent appreciable change in the internal pressure thereof under expansion and -con traction.

The movable wall 102 of thev bellowsl 99 is in permanent threaded engagement at 103 with one end of a rod 104, the opposite end of the rod being slidably mounted in a concentric recess 105 formed in a nut 106, the nut being adjustable into and out of the threaded opening 107 formed in the end wall 108 of the casing 97. The free end of the rod 95 is connected, by means of a universal joint 109, with a lever 110, this lever being e mounted on the outer free end of a crank shaft 111, said crank. shaft 111 being mounted in a suitable bearing 112 projecting inwardly from the wall of the casing 97 The-casing has been shown cylindrical in cross section in Figure 6, but of course this need not be adhered to. The inner end of the shaft 111 carries a yoke 113, the spaced arms of which engage the restricted portion 114 of a sleeve 115 which is slidably mounted on the' rod 104. A second sleeve 116 is mounted on said rod 104 and is provided with a peripheral iange 116', a coiled spring of' relatively long initial deection designated 118 being interposed between the two collars 114 and 116. 'A lever 117 is provided mounted on a crank shaft 117 carried in a suitable bearing 119 extending inwardly from the peripheral wall of the casing 97. The inner end of the shaft 117 carries a yoke member 120, the arms of which are adapted to embrace the collar 116 and to abut the peripheral ange 116 thereof, for a purpose which will hereinafter appear. The manual control .mechanism located in the cock-pit or at some other convenient point is connected to the free end o f the lever 117, an opening 121 being provided for this purpose. When at rest the end wall 102 of the bellows 99 is adapted to abut the sleeve 115 as shown in Figure 5. The nut 106 serves as a regulating stop, as will appear later. l

The sprin 118 is first adjusted by screwinor in the a justment nut 106 with the lever 117 in its left hand osition. This nut 106 is screwed in until .t e spring 118 has suiicient pressure to maintain a pressure difference 4between the interior of the expansible bellows 99 and the interior of the casing 97 of about four inches of ner'cury. For'example, with a given pressure of 29 inches -of'merl prevailing in the manifold 91 and casin 97 the throttle will be maintained substantially closed. AWhen the engine is started at ground level its rotation immediately develops a suction in the chamber 97 around the bellows 99, thereby developing an immediate expansion force against the spring 118 and .causing thel throttle to open until the pressure in the manifold reaches a point where it balances against the pressure of the Spring 118. The adjustments hereinbefore described are such that at ground level the throttle is thus made incapable of opening all the way. Any attempt on the part of the operator to speed up the engine, that is, open up the throttle` beyond a certain predetermined point will be without avail as the yoke 120,

though moved away from the collar 116, will have no effect as the collar is at that time in abutment against the nut 106. As the plane rises the reduced barometric pressure becomes effective inthe manifold 91 and in the casing 97 This results in further expansion of the bellows and consequent opening of the throttle until the pressure difference is again balanced by the spring 118. If the nut 106 is adjusted to give a difference of pressure of four inches of mercury between the interior of the bellows and the exterior of the bellows, that is, the intake manifold pressure, it will maintain this difference of pressure as the plane rises in altitude by allowingthe throttle to open further, and when the plane has reached a point where the absolute pressure of the atmosphere is approximately 25.5 of mercury, the throttle will be wide open, this of course occurring when the pilots throttle lever 117 is full over to the left in a full power position.v It will be apparent that the pilot can restrict the throttle opening at any time by merely actuating the lever 117 to increase the pressure of the spring 118. It will be obvious, therefore, that regardless of changes of engine speed the effect of the device is to maintain a fairly constant manifold pressure as determined by the initial tenson of the spring 118 against the bellows 99. The lever 117 operates on the other end of the spring 118 through the collar 116 and we might say that it governs the free length of the spring 118 so that an approximate regulation of the intake manifold vacuum is obtained by the motion of the lever'117. Thus the control of the speed of the engine cannot be abused by the pilot or other operator, as the functioning of the device is entirely beyond the control of the operator, except in so far as barometric conditions will permit. It will be obvious that at great heights, or at heights above the predetermined altitude that the device may be set for, the operator has com plete manual control of the speed of his engine, therebyA eliminating any danger of the engine failing to fire owing to the lack of functioning of the carburetor.

While, in the present application of the device and in the terminology of the description of the same We have referred to its use in connectz'on with airplane motors and the like, we, of course, do notI limit the invention to such an adaptation. The invention has a wide scope of use, and While it is best suited to the purpose described, We desire that it be understood that We contemplatemaking such changes therein as remain Within the spirit of the invention and scope of the claims in adapting the device to other uses.

We claim:

1. In combination, a carbureter adapted for connection with an intake manifold, a throttle valve controlling the flow through 'said manifold, manual means for manipulating said throttle valve, an expansible barometric chamber sealed to contain a substantially fixed pressure therein, said barometric chamber being responsive only to pressure posterior to said throttle valve, a graduated stop member movable by said barometric chamber, a projection moving with said throttle valve adapted to engage said stop member, said barometric chamber operating through said graduated stop member to limit the open position of said throttle valve in opposition to the operation of said manual means, whereby a sub-atmospheric pressure is maintained in said manifold by the restricted position of said throttle valve at predetermined atmospheric pressures.

2. In combination, a carburetor having a butterfly throttle valve, a lever connected l thereto having a4 projection, manual manipulating means connected to said lever, an expansion bellows, a lever having a shoe thereon adapted to be moved into and out of the path o movement of said projection in accordance with the position of said bellows, and saidbellows being adapted to regulate the position of said shoe in accordance with atmospheric conditions.

3, In combination, a carburetor having a throttle valve, Aa lever connected thereto a projection, moving with said levermanual manipulatingmeans connected to said lever barometrically controlled means adapted to move into and out of the path of movement of said projection in accordance With changes in atmospheric conditionsl to regulate the degree to which the throttle may be opened by said manual means, and means associated with said manual means to permit of movement of the same through its entire range regardless of the position of said barometric control means.

4. In a device of the class described, the combination with the throttle valve of an internal combustion engine, and devices connected to the throttle valve and movable therewith, of means adjustable in position and adapted to coact with said devices for limiting the extent of the opening movements of said valve, and mechanism responsive to changes in atmos heric pressure for adjusting the position o said means.

5. In combination with the usual manually operated throttle valve of an internal combustion engine, of a pressure responsive device, and means connected to the throttle valve and to the pressure responsive device for limiting the maximum open position of the throttle valve at higher atmospheric pressures corresponding to low altitudes, and

for permitting the throttle valve to be opened successively Wider at the lower atmospheric pressures, corresponding to successively higher altitudes.

In witness whereof, we hereunto subscribe our names this 8th da of June, A. D. 1920. FRANK MOCK. CHARLES J. GUSTAFSON.

MILTON E. CHANDLER. 

